1. Field of the Invention
This invention relates to an abrasive type vertical grain milling machine for cereal grains such as rice grains and wheat grains.
2. Description of the Related Art
One known milling machine of the type described is disclosed in British Patent Specification No. 1,577,979. This conventional grain milling machine will now be described with reference to FIG. 5. A spiral or helical feed roll 52 and a plurality of abrasive milling rolls 53 are mounted on a main shaft 51 rotatably mounted in an upstanding bran-removing cylinder 50 of the abrasive type vertical grain milling machine 49, and a space or gap 54, formed between any two adjacent abrasive rolls 53, serves as a jet air groove. An upper end of a grain milling chamber 55 whose main portion is defined by the bran-removing cylinder 50 and the abrasive rolls 53, communicates with a grain supply portion 56 while a lower end thereof communicates with a grain discharge portion 57.
In this conventional abrasive type vertical grain milling machine 49, grain supplied to the grain supply portion 56, is fed to the grain milling chamber 55 by the spiral roll 52, and is milled or whitened in this chamber 55 by a grain milling or whitening operation effected by the rotation of the abrasive rolls 53. The grains thus milled are discharged from the grain discharge portion 57, and powder-like matters, such as bran, produced by the grain milling operation, are discharged to the exterior of the milling machine 49 through holes or perforations 50a in the bran-removing cylinder 50 by jets of air emitted from the jet air grooves 54.
In the above-mentioned conventional abrasive type vertical grain milling machine 49, however, the grains, flowing downward in the grain milling chamber 55, is milled only by an outer peripheral or side surface 53a of each abrasive roll 53 of a hollow cylindrical or annular shape. The reason for this is that the space or gap 54 serving as the jet air groove is designed small so that the grains can not intrude into the space 54, and so that any grain milling operation can not be effected by upper and lower surfaces (i.e., end faces) 53b and 53c of the abrasive rolls 53. Therefore, in order to enhance the grain milling effect, it is necessary to increase the number of times the grains are passed through the grain milling chamber 55, and this has resulted in a drawback that the grain milling efficiency is not high.
U.S. Ser. No. 08/202,788 now U.S. Pat. No. 5,395,059 commonly assigned teaches "Spacer for abrasive roll of abrasive type grain milling machine". U.S. Ser. No. 08/274,981 now U.S. Pat. No. 5,394,792 commonly assigned teaches "Bran-removing perforated cylindrical body of abrasive type grain milling machine". U.S. Ser. No. 08/259,171 (allowed on Dec. 5, 1994) commonly assigned teaches "Resistance member adjusting mechanism of abrasive type grain milling machine". These three U.S. Patent are incorporated herein by reference thereto.